A defense attorney waited too long to ask U.S. District Judge Kurt Engelhardt to throw out the indictment of Kenneth Bowen, a New Orleans police sergeant charged with civil-rights violations in the shooting of civilians on the Danziger Bridge after Hurricane Katrina and a subsequent cover-up, federal prosecutors wrote Thursday.

View full sizeEllis Lucia, The Times-PicayuneSgt. Kenneth Bowen was photographed shaking hands with a supporter on Dec. 28, 2006.

Frank DeSalvo, the defense attorney, waited four months too long to file a brief asking the judge to quash the charges against Bowen on the grounds the case was tainted by testimony the officer was compelled to give before a state grand jury in the fall of 2006, prosecutors argued. Such a motion should have been filed in November 2010, but DeSalvo did not file it until this week, wrote Barbara "Bobbi" Bernstein, a deputy chief with the U.S. Department of Justice's civil rights division.

Bernstein also asserted that DeSalvo's argument that federal prosecutors' case was tainted because federal grand jurors were exposed to Bowen's previous testimony before a state grand jury was just wrong.

Bowen is one of five current and former police officers slated to go on trial in federal court this June. He and three other officers are accused of unjustly shooting civilians on the bridge several days after Katrina. He also is accused of working with the involved officers and NOPD investigators to cover up the attack. Five former officers have pleaded guilty in the case.

Seven officers, including three who have since pleaded guilty, were originally charged in state court for the allegedly unjustified shootings. As part of that investigation, prosecutors with the Orleans Parish district attorney's office asked Bowen to testify before a state grand jury in the fall of 2006. He refused, invoking his Fifth Amendment constitutional right against self-incrimination. Prosecutors then compelled him to testify but granted him immunity, meaning the information he provided the state grand jury could never be used against him in court.

In a motion filed Monday night, DeSalvo argued that federal prosecutors' case against his client was tainted by this state grand jury testimony, suggesting, for example, that the federal grand jury was exposed to the documents. He also argued that the case was indirectly tainted because government witnesses, such as some of the police officers who have pleaded guilty, had access to Bowen's testimony during the state case.

But Bernstein wrote that the federal government set up a "taint team" of lawyers and paralegals who made sure the immunized testimony was not used in the federal case. The government will provide more details about this team and its process in a later brief, she wrote.